1. Field of the Invention
The invention relates to a device and method of checking wear on roller chains, means being provided for tensioning a portion of the roller chain with a defined measuring load and means being provided for measuring the spacing between a given number of chain links.
2. Description of the Related Art
A gauge for measuring the spacing between two rivet heads of a chain is known from the U.S. Pat. No. 4,151,652 A and involves measuring the distance from the centre of one rivet head to the centre of the next rivet head. A defined measuring load cannot be transferred to the chain with this device. This measurement is hardly possible with a fitted chain and is fairly inaccurate even if the chain has been removed.
The DE 91 10 896 U1 describes a device for determining wear on roller chains, which consists of a rigid frame provided on one long side with two projections designed for insertion into the spaces delimited by the chain links. One of these projections is a rigid roller-support projection and the other is a measuring projection. The distance between the two projections is preferably a multiple of the length of a chain link. The device is configured as an integrally manufactured limit gauge. The measuring projection is also rigid, and the distance between the two projections is dimensioned according to a pre-selected elongation of the roller chain. A defined measuring load cannot be transferred to the chain with this device, either. It is also disadvantageous insofar as it is awkward to manufacture and can only be used for lightweight chains, such as bicycle chains. Furthermore, it is only possible to determine whether a chain is still serviceable or already too severely worn.
The DE 295 08 570 UI and the GB 2 396 420 A describe similar devices for measuring wear on roller chains, comprising a frame with a measuring projection, which has scale markings, and a roller-support projection. Although a numerical value is obtained with this device, the measurement is inaccurate. Plus, it is again impossible to transfer a defined measuring load to the chain with this device.
A device for determining wear on roller chains is known from the DE 298 17 329 UI, which consists of a frame provided on one long side with two projections designed to fit into the spaces delimited by the chain links. One of these projections is a rigid roller-support projection and the other a measuring projection. The distance between them is a multiple of the length of a chain link and/or corresponds to a pre-selected elongation or extension of the roller chain. The frame is formed by two jointed parts. If the parts form a straight line when the device is fitted against the chain, this indicates that the chain is worn. Here too, it is only possible to determine whether a chain is still serviceable or already too severely worn. It is not possible to transfer a defined measuring load to the chain with this device.
The U.S. Pat. No. 4,092,781 describes a device for measuring roller-chain elongation caused by wear. The chain is tensioned between two arms of the device by means of a spring and the spacing between a given number of chain links in a reference chain compared with the corresponding spacing in the chain under test. The result is inaccurate. A further disadvantage here is the need for a reference chain. A defined measuring load cannot be transferred to the chain with this device, either. A similar solution is known from the US 2010/162583 A1.